Role of the drought
The water deficit and cyclical droughts are one of the causes of the expansion of desalination in Spain.
Barcelona and its metropolitan area use mainly two basins: the Ter basin at 55% and the Llobregat basin at 38%. In both basins, the upper part is controlled by reservoirs that modulate the necessary water resources. The drought is defined according to the level of filling of these basins, for example it is declared to allow the limitation of certain activities when the filling is below the threshold of 30%. When major droughts occur, groundwater extraction from aquifers and desalination of sea water are required, which makes the management of water resources even more complex.
Dates of the last droughts
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1979-1983 / 1990-1995 / 2000 / 2002 / 2005 / 2008 / 2016-2017
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A 2020 study by Edwar Forero-Ortuz et al. shows that cyclical drought episodes are expected to occur every 20 years with more than one year of persistent drought conditions, with models pointing to a decrease in global water availability. The authors explain that desalination can be used in the event of a shortage, that it is a technology that has the capacity to do so, but that the cost must be put into perspective: the average unit cost of producing desalinated water (0.58€/m3) is four times higher than the cost of producing drinking water in the drinking water treatment plant (0.14€/m3). This raises the question of the relevance of such an infrastructure as a desalination plant for only 8% of the consumption and periods of shortage, while alternative solutions are possible such as reducing drinking water consumption or planning and implementing water recycling and reuse (19).